In Reply.—Under electron microscopy, the electron micrograph showed that the tumor cells were plasma cells by the presence of a round, eccentric nucleus with clumped chromatin at the periphery, prominent nucleolus, abundant arrays of rough endoplasmic reticulum with some distended cisternae, and a Golgi complex. We did examine a formaldehyde-fixed tissue specimen. The methyl green-pyronine stain did not give the expected result, and it was not possible to perform the immunoperoxidase procedures to demonstrate cytoplasmic immunoglobulin production.